Solar photovoltaic arrays, often referred to as solar panels, convert solar radiation into electricity. The costliest and most time-consuming process involved in the manufacture of thin-film silicon photovoltaics is thin-film deposition. For high volume manufacturing applications, thin-film deposition is often accomplished through a plasma-enhanced chemical vapor deposition (PECVD) process. However, current PECVD processes are limited by slow thin-film deposition rates, roughly one nanometer per second, and moreover, are often unable to eliminate thin-film defects that dramatically decrease solar conversion efficiency.
Most current PECVD processes utilize capacitive radiofrequency (RF) discharge plasma reactors. However, capacitive RF discharge plasma reactors exhibit numerous undesirable features when scaled to large sizes and high power, including large transient voltages, discharge non-uniformities, and generation of arcs and surface defects between active parallel plates. Therefore, in order to limit undesirable plasma characteristics, capacitive RF discharge plasma systems are operated at relatively low plasma density (e.g. 1010 cm−3) thereby severely limiting rates of plasma-enhanced chemical vapor deposition (PECVD) and plasma etching. Microwave plasma sources can be operated at considerably higher densities (e.g. 1012 cm−3) but nevertheless exhibit their own undesirable characteristics, which include engineering difficulties associated with scaling the devices to large sizes, plasma non-uniformities, and instability at high deposition rates.